20 April, 2009

Spring Thing

A few years ago I had a frame with horizontal dropouts that had the usual unsightly fender line. The chain stay bridge was set far forward so as to allow enough room for the wheel to be removed. Of course I couldn't shim the fender to the proper position because that would make removing the wheel impossible, at least without deflating the tire. So I decided to try a spring instead of a shim. The spring, and a bolt, held the fender at the proper distance from the tire. But by compressing the spring the fender flexes out of the way and the wheel can be dropped off.


It worked great and I congratulated myself on my clever invention, not realizing that others had previously "invented" exactly the same trick. In any case, this photo might be useful to some who ride fendered bikes with horizontal dropouts. By the way, the new VO Polyvalent frame was designed with this little trick in mind.

If you try this, get a very stiff spring so the fender won't rattle. And be sure to use a Nylock nut; regular nuts will loosen. I wonder if we should sell a little Spring Thing kit?

31 comments:

Anonymous said...

a "spring thing kit" would be nice.. especially if you carefully chose nicer stainless hardware etc.. it could also include two leather washers.

Anonymous said...

Thanks for the great tip, I have been looking for an answer to this question for over a month now, i figured there had to be some clean way. As far as the kit, I think there is probably too much variance on frames to make it work (i know the one in the picture would not work on my bike, an old Carleton made Raleigh Super Tourer - though the concept is good) Keep up the good work,

Dan

Leighton said...

I "invented" the similar thing five years ago or so to solve the same problem. In my case I used a length of stainless steel strapping bent into a U-shape. An early version is here: http://tinyurl.com/springthing.

While it worked well for wheel removal and getting a good fender line, this design had two problems: First, the front end of the fender is too high, and let water get on the crank; second, the strap's end at the chainstay bridge snapped off after a while -- it was too close to the tire, and thus had to bend sharply when the wheel was removed. Do that enough, and it broke off.

The newest design (don't have a picture) attaches at the front of the chainstay bridge, heads down, and then curves back up to the rear of the fender, which is now between the stays. Works perfectly in all respects.

patates frites said...

I'm not sure I understand how the "spring thing" works. The picture shows a bolt inside the spring. Even if you push the fender and compress the spring, the bolt does not compress and it sticks out. So now you don't have the fender as an obstacle, but you still have the bolt. How does the tire clear the bolt?

Chris Kulczycki said...

Patates, The bolt slides forward when the spring is compressed. It's not threaded into the bridge.

WCrawford said...

Yes, and it should be called "Little Spring Thing Kit"

Anonymous said...

Stainless good, how about a rubber bellow that is captured by the washers, forget the leather or fibre washers then.

Leighton said...

For what it's worth, here are some variations on the theme: http://tinyurl.com/springthing.

The first is the original version, with the drawbacks mentioned. The second is modified to get a lower start point for the rear fender -- but I misremembered being able to connect on the front of the bridge; can't here, as the mount is one the rear. (With a drilled-through hole one could.) The last is the latest version, with the springthing wrapped around the bridge; this is nice because it has some swing to it. Swingspringthing?

Anonymous said...

Spring-thing looks good.
I worked for a guy in the mid-1980's who used to do the exact same thing with his SKS fenders.

I am just concerned that the fender spring might affect the resonance frequency of my frame and that it might reduce the "planing". Will different levels of springiness be offered to match the levels of how much we believe in "planing", or not ?

Perhaps if the bolt was threaded to an uncommon French size then everything would probably work better.

Tom said...

" Yes, and it should be called "Little Spring Thing Kit" "

I'd prefer to reference part number FE-0035. but thats just me.

Anonymous said...

ah, you are a clever one, 007!

a brillant idea!!!

Jim G said...

Won't flexing a metal fender lead to cracking?

Dave said...

This is brilliant. I haven't put much thought into a solution, but I've certainly been unsatisfied with my current wine cork-as-spacer set up. I'm going to rig something like this right away.

Dave

Andy M-S said...

Neat. I thought about doing something like this, but I was worried about rattle from the spring, so...I have a similarly-configured ("sliding") bolt, and then a black rubber stopper(remember chem lab?). Turns out you can get these stoppers even at small hardware stores. I bored a hole through the stopper, then slit one side down to the bore. I press this over the bolt, between the chainstay bridge and the fender, and all is well.

When I need to remove a wheel, I can pry out the stopper, and the bolt and fender slide forward to allow removal.

Leighton said...

"Won't flexing a metal fender lead to cracking?"

I've never had problems. Have set up three fendered bikes -- Berthouds, Honjos, and SKSs, respectively -- with flexible mounts and all have been just fine.

robatsu said...

Clever. Another reason to use it, and it would be what sells me (I'll stick w/deflating tires) is that I've had problems with fatigue failure of long mounting bolts when the distance between the fender and the stay bridge is much more than an inch or so.

This was a chronic problem on my Trek 620, which had a gap in excess of 2 inches. 50 miles on the C&O towpath could be enough to fail a new bolt. I'm embarassed to describe my solution, although it worked...

Anyhow, this setup would definitely be one solution for people who have a fairly large fender/stay gap and regularly do rough stuff riding.

Garth said...

Any thoughts on routing dynamo hub wires to a tail light? I've thought of the tape method- others?

I've thought of possibilities using a flat wire: similar to what you might see on some circuit boards. It would be more discrete for the downtube between the cables.

Epoxy the wire to the inside of the rear fender?

It would be nice if the downtube was drilled for a wire, but it is not. Examples of this that I've seen also involve a reinforcement brass.

I believe there must be a clever solution that is both elegant (hidden wire) and dependable.

Thanks,
Garth

Uncle Ankle said...

Over here in the old country taillight wires used to be pressed into the folded edge of the rear fender.

robatsu said...

When I used to run a dynamo rear, what I did was drill another hole in the fender near the chainstay bridge mount hole, and then insert a rubber grommet.

The wire coming from the dynamo passed through this and ran along the underside of the fender to a similar hole near the taillight.

The wire was kept in place on the underside of the fender with duct tape. The tape never came loose, ever a little bit at the edges, despite lots of wet weather/muddy use. It helps if the underside of the fender is squeaky clean when putting down the duct tape.

The hole grommets keep the wire from getting damaged by the sharp end of the fender. I also used a little heavier gauge of wire w/thicker plastic insulation, like one strand of what is typically found on cords to things like tv's, vcrs, etc, the thought being that this is a little more rugged for being pelted with gravel, sand, etc. Maybe this was overkill, but I never had any problems and it was a very clean, inobtrusive setup.

patates frites said...

OK, Chris, now I get how it's supposed to work. But in the picture it looks as though the allen bolt that holds the kickstand would prevent the bolt from sliding forward. Is it just the angle of the picture or what?

kilroy said...

Greetings,

You guys and gals at Velo Orange are using your heads. I've been using bubble gum, baling wire and duct tape all these years. The spring thing revelation is beyond fantastic. Now I can lead a productive life!

Anonymous said...

3M sells automotive striping tape in many widths. I have some 3/4" in black that I bought for a small project. That stuff is tough! Just ask any body shop employee who has ever had to remove some of it. I've been meaning to try using it to hold taillight wires inside a rear fender, but like a lot of other experiments, it's still waiting near the bottom of a long list. I'd be happy to dig out the roll and send Chris several feet of it if he wants to try it. VO could buy it by the roll and sell it by the foot, like cable housing. A whole roll is not cheap. I know it comes in silver.

Anonymous said...

The welds on that bike look pretty good!

Anonymous said...

How far can the bolt come in if the allen bolt sits in its path? It looks like the movement of the fender forward is responsible for most of the additional room.

El Duke said...

Yes, please sell it. Will save time having to search for the proper parts at the hardware store.

Garth said...

Thank you for your responses! The 3M striping tape convinces me that I can do this dependably as well as aesthetically "clean" enough to make a wired tail light acceptable. I also think it may be more durable than the duct tape for underneath the fender as well. I suppose if I had to change it every few years as a maintenance item, that would also be acceptable.

As for VO, I think it would be super if the down tubes were drilled and reinforced like many of the better city bikes from Europe and Japan are.

Oh. My other idea for the fender was to epoxy a thin metal tube to the inside of the fender, to house and protect the wire. A coaxial wire is pretty tough though, too.

I'll send an update once I get it all done.

Sincerely,
Garth

Anonymous said...

Some people say that fender mounted lights are bad because they get damaged too quickly but I've never found that to be the case. The big rack mounted B&M lights often hit whatever the bike is leaned up against, hit the pavement whenever the bike falls and are mounted rigidly to the rack, whereas the fender mounted light can move away from an impact as the fender flexes in response. It's a sort of suspension for the light. In my experience, the lens of a fender mounted light is longer lived. I've worked on quite a few old dutch and german bikes and the fender lights and rear wires were never a problem, but then the set up was always done right.

Chris Kulczycki said...

On the bike in the photo the kickstand bolt is just far enough back to allow the wheel to be removed. But if you need more room you can use a button-head, or a low profile, 10mm bolt in place of the one that comes with the kickstand.

david_nj said...

This is very clever, but the one thing that gives me pause is, I've noticed that the fenders can get very wobbly unless there are two hard mounting points.

Nevertheless, I'm buyin' one of these city bike frames. They're really gonna be cool!

david_nj said...

Oh, also: just make the rear tab of the Spring Thing plate a bit higher, and then the two bolts won't have interference problems.

My $.02

Charles said...

That's pretty awesome. Any ideas though for a frame that doesn't have the bridge between the stays there though? I have a fixed/free frame that has no small bridge there, and I've generally used zip ties, which I confess is not quite the aesthetic I'd like. But I haven't been able to come up with anything else to hold that end of the fender.